Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already mark readOnlyHint=true, but the description adds valuable behavioral details beyond that: it returns file counts, sizes, and last-touched timestamps, and it explicitly excludes the vault by design. This gives the agent expectations about data scope and content without contradicting the annotation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, each earning its place. The front-loaded questions directly state the tool's value, the definition of a collection clarifies terminology, and the vault exclusion is a critical caveat. No filler or repetition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a parameterless list tool, the description is complete: it states the exact return content (counts, sizes, last touched), defines the resource type, and discloses the exclusion of the vault. No output schema exists, but the description sufficiently sets expectations for what the agent will receive.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so the schema trivially covers everything. Per the rubric, 0 params merits a baseline of 4. The description adds no parameter-specific information, but none is needed since there are none.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'list' and resource 'collections', and immediately answers the common questions an agent would ask (what do I have, which are empty, how big). It explicitly distinguishes collections from one-off transfers and names the vault exclusion, so it separates cleanly from sibling tools like list_transfers and get_collection.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use this tool by contrasting collections with one-off transfers and noting the vault is never included, which steers an agent toward the correct sibling for transfers or vault data. It does not explicitly say 'use this when you need an overview' but the context is clear enough to guide selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.